This thesis explores a conceptual methodology for studying archaeological sites in fluvial settings. The methodology stems from geoarchaeology, an approach to the past that focuses upon the geomorphic context of artifacts or the application of geological principles and techniques to the solution of archaeological problems. The paper will examine its application to fluvial systems in two different geomorphic environments, the Oklawaha River in Florida and the Earn River Valley in Scotland. In these different environmental settings, the geoarchaeological approach makes use of different kinds of evidence available to it. Survey in submerged and eroding river margins offers additional information on site distribution and density within the landscape that can go unnoticed by traditional terrestrial surveys. Through conceptualization and application of the methodology that has developed from these studies, the arbitrary land/water interface can effectively be erased from research areas and rivers can begin to be viewed not as permanent and non-moving barriers, but as significant and dynamic components of the archaeological landscape.